We remodeled and put in a tankless water heater in fall of '06. The guy who installed it was here to do a small plumbing job and mentioned that the factory recommends a descaling flush once a year (which he'll do for $200). I can't find anything in the manual about such flushing so am wondering what any of you who might have had experience with these systems have to say. I don't doubt that there'll be scale build- up over time; I'm mostly wondering about frequency (and cost).
Thanks.
Lynn Willis San Diego